The present application relates to a method of forming nanoscale structures, and more particularly to a method of forming customized line structures using a composite pattern of a lithographically defined template pattern and a directed self-assembly pattern of a self-assembling material that is self-aligned with the template pattern.
Directed self-assembly (DSA) of block copolymers is an emerging patterning technology for generating narrow lines in integrated circuits (ICs) with smaller pitches beyond the current optical lithographic limit. However, IC designs typically include customized elements such as aperiodic, isolated, or discontinuous lines. While DSA has shown promise in creating large areas of dense line patterns with constant pitch, forming lines of varying pitches and/or dimensions is difficult. The most straightforward way to obtain these lines using DSA is to trim the DSA-generated pattern employing lithographic masks. Unfortunately, modification of lines corresponding to individual self-assembled domains in the DSA pattern is very challenging given the limited resolution of available lithography tools. More critically, as the size of individual self-assembled domains useful for patterning is approaching the scale of the overlay error associated with misalignment of the lithographic trim pattern to the self-assembled pattern, patterning errors of such commensurate scale are detrimental to device yield, performance, reliability, and uniformity. Therefore, a method for customizing patterns generated by DSA of a self-assembling material without involving additional overlay alignment steps is needed.